ETYM Latin illicitus; pref. il- not + licitus, p. p. of licere to be allowed or permitted: cf. French illicite. Related to In- not, and License.
(Homonym: elicit).
Contrary to accepted morality (especially sexual morality) or convention.

1. Contrary to or prohibited by or defiant of law
2. Having no legally established claim; SYN. wrongful.
3. Not morally right or permissible
4. Not conforming to legality, moral law, or social convention
5. Contrary to or prohibited by or defiant of law